1. Field of the Invention
The invention relates to an antenna, a connection device, a coupler and a substrate laminating method which are used for a premises radio communication system for instance.
2. Description of the Related Art
An antenna to be used for this type of system is required to tilt beams in a desired direction. For example, "Oblique Beam Achieving Mode Compounding Type Circular Microstrip Antenna" by Tsuneyoshi TERADA, Autumn Meeting of Electronic Information Communication Society, 1992 (Japan) B-84 describes a microstrip antenna which tilts beams in a desired direction. The antenna described in this paper has a plurality of ring microstrip antennas formed concentrically in the same plane, one of the microstrip antennas is excited in a TM110 mode, the other microstrip antennas are excited in a high-order mode such as a TM210 mode, and the radiation patterns of these antennas are combined, thus beams from the front direction are tilted.
But, since electric power is required to be supplied to the plurality of ring microstrip antennas at a desired exciting amplitude difference and phase difference, an antenna element and a feeder circuit are separately needed, resulting in a high production cost. And, since the number of components is increased, downsizing is hindered.